I. Field of the Invention
The present invention relates to coupling devices that enable various premanufactured magnifying lens arrangements to be coupled to a night vision device, thereby increasing the power of magnification for the night vision device. More specifically, the present invention relates to a modular coupling system wherein various magnifying lens arrangement for differing shapes and sizes and from different manufactures can be simply and easily coupled to an unassociated night vision assembly.
II. Prior Art Statement
Many types of optical devices, such as cameras, video cameras, projectors and the like include a threaded aperture surrounds the objective lens of that device. The presence of the threaded aperture enables secondary optical devices to be attached in front of the objective lens along the optical path of the optical device. For instance, many cameras have objective lenses that are adapted to receive various wide-angle, telescopic and/or light filter arrangements. Similarly, night vision devices are also commercially available that can be directly mounted to a camera, video camera or the like, so that pictures can be taken during night time or other low light conditions. In view of the multitude of optical devices that can be selectively attached to the various cameras, video cam recorders and the like, it will be understood that a large number of coupling devices exist in the prior art. However, there are no standards to which the all couplings conform. Consequently, each manufacturer may require a different unique coupling device to join any given peripheral device to any given optical assembly. The complexity of the field of optical component adapters becomes even more apparent when it is recognized that many optical assemblies require bayonet style connectors while still others require screw type connectors. As a result, whenever a person buys a secondary optical device to join to a specific camera, VCR or the like, that person must buy a specific coupling adaptor to properly join those two components together. That coupling is typically designed specifically for that secondary optical device and does not fit any other secondary optical device that may be available from another manufacturer.
Finding the proper coupling device for popular cameras and popular lens systems is not difficult. However for specialty optics, such as night vision assemblies, the task becomes far more complex. First, night vision devices do not have a single focus system as do most cameras, telescopes and the like, (i.e., the objective lens focuses the image onto the film or at the ocular). Rather, most night vision devices have double focus system where, first, the objective lens focuses light onto an image intensifier tube and second the image made by the tube is focused at the ocular. Accordingly, unassociated lens arrangements cannot be randomly attached to night vision devices if those lens arrangements change the objective lens focus beyond the range of adjustment embodied by the optics of the night vision device. As such, in many prior art night vision devices the optics between the objective lens and the image intensifier tube must be changed with customized optics in order to properly change the optical power of the night vision device. Many night vision devices must therefore be fully disassembled and reassembled in order to change the power of magnification for the assembly. As a consequence of such a complicated optical configuration, many night vision devices do not even provide a means to connect a secondary optical assembly to the night vision device. Other night vision devices that do have removable telescopic assemblies utilize custom telescopic assemblies that are specifically designed to be compatible to the remaining optics in the night vision device.
Another problem incurred when attempting to attach unassociated commercial lens assemblies to night vision devices is that night vision devices have small objective lenses as compared to cameras, video cameras and the like. For example many 35 mm cameras have objective lenses with diameters in the range of 50 mm. As such, any secondary optics made to be added to such a camera also are typically in the 50 mm range. Alternatively, night vision devices that utilize a Generation III image intensifier tube typically only have an objective lens in the 25 mm range, which is about half of that of the camera. Accordingly, the size of the night vision devices is often too small to enable a typical camera lens to be coupled to it. Similarly, the size differentials between the camera lenses and the night vision device result in an incompatible optical arrangement.
Since night vision devices either embody no coupling means for external optics or embody customized optical arrangements for specialized external optics, there is no way available to join unassociated commercially available lens arrangements to a night vision assembly. This is true simply because if an unassociated commercially available lens arrangement were joined to a night vision assembly, it would probably have an incompatible optical design and would not work. As a result, no coupling devices have been needed.
An exception to the general rule that external lens arrangements are incompatible with night vision assemblies occurs when the external lens arrangement creates a collimated or otherwise a focal image. In such a circumstance the light entering the night vision device is generally parallel and does not produce an adverse effect upon the optical design of the night vision device. There are commercially available telescopic lenses available in the prior art that create a generally a focal output. However, each such telescopic lens is unique with its own shape, size and coupling system, most all of which are incompatible with the night vision device.
It is therefore the objective of the present invention to provide a modular coupling device whereby unassociated a focal telescopic lens arrangements can be quickly and economically coupled to a night vision device, thereby selectively changing the optical power of the night vision device.
It is a further objective of the present invention to provide for a night vision device with a modular secondary lens system, whereby the optical power of the night vision device can be changed by selectively replacing an external supplemental lens system coupled to the night vision device.